and ufo pics drawn by children are deemed worthy of keeping? vs something they went so far as to ask the US government about?It might be thought unlikely that papers or photographs concerning such an important case as Calvine would just be junked, but this assumes that their importance is recognised by the officials responsible for decisions on retention or disposal.
My guess is they either did not make physical copies before returning the negatives (communication breakdown), or maybe they just stuck them in a different file and too much time passed before anyone asked about it so the memory was lost in time.
Nick Pope worked the "UFO team" (seemingly) 1991-1994. that isnt throwing away files that are 10 years old
From 1991 to 1994, he worked in Secretariat (Air Staff) Sec (AS) 2a more commonly known as the "UFO desk", where his duties included investigating reports of UFO sightings, to see if they had any defence significance. At the time, while the Ministry of Defence stated that it "remains totally open-minded about the existence or otherwise of extraterrestrial lifeforms", it also stated that there was no evidence to suggest that any UFO sightings posed any threat to the UK or that they were extraterrestrial in origin. It is clear from material that Pope wrote whilst still at the MoD that he did not share the MoD's view that conventional explanations could be found for all UFO sightings.